Mitigation of CaCO₃ fouling on heat exchanger surface using green functionalized carbon nanotubes (GFCNT) coating

Deposition of mineral foulants on the heat exchanger surface increases the thermal resistance and shortens the operating service life of heat exchangers. The inverse solubility characteristics of some mineral salts in the cooling water cause intensive mineral fouling on heated heat exchanger surfaces. The formation of fouling deposits starts when mineral salts in water crystallize on the heated surface. In this study, a coating of MWCNT from the suspension of water, gum Arabic and MWCNT was applied on the surface of the heat exchanger to mitigate CaCO₃ fouling. A 300 mgL⁻¹ CaCO₃ supersaturated solution was prepared and used for the foulant deposition on the heat transfer surfaces and analysis. The Field Emission Scanning Electron Microscopy (FESEM) was used for the investigation of CaCO₃ depositions on the heat exchanger surface, its surface morphology, and develop correlation with the crystal growth, morphology and the coating introduced inhibition effect on fouling. The results revealed that the CaCO₃ crystal formation can be considerably retarded using MWCNT coating layer as a fouling mitigation approach.